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# Word Problems

(1)

If Ramon can mow the entire lawn in x -3 hours, then how much of the lawn does he mow per hour?

(2)

Toxic pollutants. The annual cost in dollars for removing p% of the toxic chemicals from a town's water supply is given by the formula C(p) =500, 000/100-p

a) Use the accompanying graph to estimate the cost for removing 90% and 95% of the toxic chemicals.
b) Use the formula to find C(99.5) and C(99.9).
c) What happens to the cost as the percentage of pollutants removed approaches 100%?

(3)

Magazine sales. Henry sold 120 magazine subscriptions in x days.

a) Write a rational expression for the rate at which he sold the subscriptions.
b) Suppose that he continues to sell at the same rate for 5 more days. Write a rational expression for the number of magazines sold in those 5 days.

#### Solution Preview

***Question 1***

If Ramon can mow the entire lawn in x -3 hours, then
how much of the lawn does he mow per hour?

Ramon can mow the whole lawn (100% of it) in x - 3 hours. We want to know how much he can mow in 1 hour. Let's call this amount "y". We can set up an equation:

100 percent y percent
-------------- = --------------
(x - 3) hours 1 hour

We want to solve for y:

100/(x - 3) = y/1
100/(x - 3) = y

So, in one hour, Ramon can mow 100/(x - 3) percent ...

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